Most audio shops will have that in a look up chart. Why the speakers?

I've always found the weak link to be the deck and lack of sub woofers.

If you want it to sound a lot better buy a good deck that has a built in crossover, and install a 10" woofer and amp.

91 YJ
2 Seater Sand Rail
Handfull of other fun toys...
And a brand new, spit shined, B.S.
Oh, and a job to boot.